/**
 *@note Copyright 2012-2022 CETHIK All Rights Reserved.
 *@brief 膨胀层实现文件
 *@author tuyinan
 *@data 2022-04-xx
 */
#include <costmap_2d/costmap_math.h>
#include <costmap_2d/footprint.h>
#include <costmap_2d/inflation_layer.h>

#include <algorithm>
#include <boost/thread.hpp>

using costmap_2d::INSCRIBED_INFLATED_OBSTACLE;
using costmap_2d::LETHAL_OBSTACLE;
using costmap_2d::NO_INFORMATION;

namespace costmap_2d {

InflationLayer::InflationLayer()
    : resolution_(0),
      inflation_radius_(0),
      inscribed_radius_(0),
      weight_(0),
      inflate_unknown_(false),
      cell_inflation_radius_(0),
      cached_cell_inflation_radius_(0),
      seen_(NULL),
      cached_costs_(NULL),
      cached_distances_(NULL),
      last_min_x_(-std::numeric_limits<float>::max()),
      last_min_y_(-std::numeric_limits<float>::max()),
      last_max_x_(std::numeric_limits<float>::max()),
      last_max_y_(std::numeric_limits<float>::max()) {
  inflation_access_ = new boost::recursive_mutex();
}

void InflationLayer::onInitialize() {
  boost::unique_lock<boost::recursive_mutex> lock(*inflation_access_);

  current_ = true;
  if (seen_) {
    delete[] seen_;
  }
  seen_ = NULL;
  seen_size_ = 0;
  need_reinflation_ = false;

  setInflationParameters(
      (*configNode_).getValueOfKey<double>("inflation_radius", 0.0),
      (*configNode_).getValueOfKey<double>("cost_scaling_factor", 0.0));
  matchSize();
}

void InflationLayer::matchSize() {
  boost::unique_lock<boost::recursive_mutex> lock(*inflation_access_);
  costmap_2d::Costmap2D* costmap = layered_costmap_->getCostmap();
  resolution_ = costmap->getResolution();
  cell_inflation_radius_ = cellDistance(inflation_radius_);
  computeCaches();

  unsigned int size_x = costmap->getSizeInCellsX(),
               size_y = costmap->getSizeInCellsY();
  if (seen_) {
    delete[] seen_;
  }
  seen_size_ = size_x * size_y;
  seen_ = new bool[seen_size_];
}

void InflationLayer::updateBounds(double robot_x, double robot_y,
                                  double robot_yaw, double* min_x,
                                  double* min_y, double* max_x, double* max_y) {
  if (need_reinflation_) {
    last_min_x_ = *min_x;
    last_min_y_ = *min_y;
    last_max_x_ = *max_x;
    last_max_y_ = *max_y;
    // For some reason when I make these -<double>::max() it does not
    // work with Costmap2D::worldToMapEnforceBounds(), so I'm using
    // -<float>::max() instead.
    *min_x = -std::numeric_limits<float>::max();
    *min_y = -std::numeric_limits<float>::max();
    *max_x = std::numeric_limits<float>::max();
    *max_y = std::numeric_limits<float>::max();
    need_reinflation_ = false;
  } else {
    double tmp_min_x = last_min_x_;
    double tmp_min_y = last_min_y_;
    double tmp_max_x = last_max_x_;
    double tmp_max_y = last_max_y_;
    last_min_x_ = *min_x;
    last_min_y_ = *min_y;
    last_max_x_ = *max_x;
    last_max_y_ = *max_y;
    *min_x = std::min(tmp_min_x, *min_x) - inflation_radius_;
    *min_y = std::min(tmp_min_y, *min_y) - inflation_radius_;
    *max_x = std::max(tmp_max_x, *max_x) + inflation_radius_;
    *max_y = std::max(tmp_max_y, *max_y) + inflation_radius_;
  }
}

void InflationLayer::onFootprintChanged() {
  inscribed_radius_ = layered_costmap_->getInscribedRadius();
  cell_inflation_radius_ = cellDistance(inflation_radius_);
  computeCaches();
  need_reinflation_ = true;
}

void InflationLayer::updateCosts(costmap_2d::Costmap2D& master_grid, int min_i,
                                 int min_j, int max_i, int max_j) {
  boost::unique_lock<boost::recursive_mutex> lock(*inflation_access_);

  if (!enabled_ || (cell_inflation_radius_ == 0)) {
    return;
  }

  unsigned char* master_array = master_grid.getCharMap();
  unsigned int size_x = master_grid.getSizeInCellsX(),
               size_y = master_grid.getSizeInCellsY();

  if (seen_ == NULL) {
    seen_size_ = size_x * size_y;
    seen_ = new bool[seen_size_];
  } else if (seen_size_ != size_x * size_y) {
    delete[] seen_;
    seen_size_ = size_x * size_y;
    seen_ = new bool[seen_size_];
  }
  memset(seen_, false, size_x * size_y * sizeof(bool));

  // We need to include in the inflation cells outside the bounding
  // box min_i...max_j, by the amount cell_inflation_radius_.  Cells
  // up to that distance outside the box can still influence the costs
  // stored in cells inside the box.
  min_i -= cell_inflation_radius_;
  min_j -= cell_inflation_radius_;
  max_i += cell_inflation_radius_;
  max_j += cell_inflation_radius_;

  min_i = std::max(0, min_i);
  min_j = std::max(0, min_j);
  max_i = std::min(int(size_x), max_i);
  max_j = std::min(int(size_y), max_j);

  // Inflation list; we append cells to visit in a list associated with its
  // distance to the nearest obstacle We use a map<distance, list> to emulate
  // the priority queue used before, with a notable performance boost

  // Start with lethal obstacles: by definition distance is 0.0
  std::vector<CellData>& obs_bin = inflation_cells_[0.0];
  for (int j = min_j; j < max_j; j++) {
    for (int i = min_i; i < max_i; i++) {
      int index = master_grid.getIndex(i, j);
      unsigned char cost = master_array[index];
      if (cost == LETHAL_OBSTACLE) {
        obs_bin.push_back(CellData(index, i, j, i, j));
      }
    }
  }
  // Process cells by increasing distance; new cells are appended to the
  // corresponding distance bin, so they can overtake previously inserted but
  // farther away cells
  std::map<double, std::vector<CellData> >::iterator bin;
  for (bin = inflation_cells_.begin(); bin != inflation_cells_.end(); ++bin) {
    for (int i = 0; i < bin->second.size(); ++i) {
      // process all cells at distance dist_bin.first
      const CellData& cell = bin->second[i];

      unsigned int index = cell.index_;

      // ignore if already visited
      if (seen_[index]) {
        continue;
      }

      seen_[index] = true;

      unsigned int mx = cell.x_;
      unsigned int my = cell.y_;
      unsigned int sx = cell.src_x_;
      unsigned int sy = cell.src_y_;

      // assign the cost associated with the distance from an obstacle to the
      // cell
      unsigned char cost = costLookup(mx, my, sx, sy);
      unsigned char old_cost = master_array[index];
      if (old_cost == NO_INFORMATION &&
          (inflate_unknown_ ? (cost > FREE_SPACE)
                            : (cost >= INSCRIBED_INFLATED_OBSTACLE))) {
        master_array[index] = cost;
      } else {
        master_array[index] = std::max(old_cost, cost);
      }

      // attempt to put the neighbors of the current cell onto the inflation
      // list
      if (mx > 0) {
        enqueue(index - 1, mx - 1, my, sx, sy);
      }
      if (my > 0) {
        enqueue(index - size_x, mx, my - 1, sx, sy);
      }
      if (mx < size_x - 1) {
        enqueue(index + 1, mx + 1, my, sx, sy);
      }
      if (my < size_y - 1) {
        enqueue(index + size_x, mx, my + 1, sx, sy);
      }
    }
  }

  inflation_cells_.clear();
}
inline void InflationLayer::enqueue(unsigned int index, unsigned int mx,
                                    unsigned int my, unsigned int src_x,
                                    unsigned int src_y) {
  if (!seen_[index]) {
    // we compute our distance table one cell further than the inflation radius
    // dictates so we can make the check below
    double distance = distanceLookup(mx, my, src_x, src_y);

    // we only want to put the cell in the list if it is within the inflation
    // radius of the obstacle point
    if (distance > cell_inflation_radius_) {
      return;
    }

    // push the cell data onto the inflation list and mark
    inflation_cells_[distance].push_back(CellData(index, mx, my, src_x, src_y));
  }
}

void InflationLayer::computeCaches() {
  if (cell_inflation_radius_ == 0) {
    return;
  }

  // based on the inflation radius... compute distance and cost caches
  if (cell_inflation_radius_ != cached_cell_inflation_radius_) {
    deleteKernels();

    cached_costs_ = new unsigned char*[cell_inflation_radius_ + 2];
    cached_distances_ = new double*[cell_inflation_radius_ + 2];

    for (unsigned int i = 0; i <= cell_inflation_radius_ + 1; ++i) {
      cached_costs_[i] = new unsigned char[cell_inflation_radius_ + 2];
      cached_distances_[i] = new double[cell_inflation_radius_ + 2];
      for (unsigned int j = 0; j <= cell_inflation_radius_ + 1; ++j) {
        cached_distances_[i][j] = hypot(i, j);
      }
    }

    cached_cell_inflation_radius_ = cell_inflation_radius_;
  }

  for (unsigned int i = 0; i <= cell_inflation_radius_ + 1; ++i) {
    for (unsigned int j = 0; j <= cell_inflation_radius_ + 1; ++j) {
      cached_costs_[i][j] = computeCost(cached_distances_[i][j]);
    }
  }
}

void InflationLayer::deleteKernels() {
  if (cached_distances_ != NULL) {
    for (unsigned int i = 0; i <= cached_cell_inflation_radius_ + 1; ++i) {
      if (cached_distances_[i]) {
        delete[] cached_distances_[i];
      }
    }
    if (cached_distances_) {
      delete[] cached_distances_;
    }
    cached_distances_ = NULL;
  }

  if (cached_costs_ != NULL) {
    for (unsigned int i = 0; i <= cached_cell_inflation_radius_ + 1; ++i) {
      if (cached_costs_[i]) {
        delete[] cached_costs_[i];
      }
    }
    delete[] cached_costs_;
    cached_costs_ = NULL;
  }
}

void InflationLayer::setInflationParameters(double inflation_radius,
                                            double cost_scaling_factor) {
  if (weight_ != cost_scaling_factor || inflation_radius_ != inflation_radius) {
    // Lock here so that reconfiguring the inflation radius doesn't cause
    // segfaults when accessing the cached arrays
    boost::unique_lock<boost::recursive_mutex> lock(*inflation_access_);

    inflation_radius_ = inflation_radius;
    cell_inflation_radius_ = cellDistance(inflation_radius_);
    weight_ = cost_scaling_factor;
    need_reinflation_ = true;
    computeCaches();
  }
}

}  // namespace costmap_2d
